This invention relates to chemical thermal packs. More specifically, this invention relates to hot or cold thermal packs of the type placed in contact with the body to relieve pain, reduce swelling and the like.
U.S. Pat. No. 3,175,558 to Caillouette et al. discloses a thermal therapeutic pack useful either as a heat pack or a cold pack wherein the bag that contains chemicals providing the thermal effect is insulated from the body by an absorbent material.
U.S. Pat. No. 3,874,504 to Verakas discloses a chemical thermal pack that consists of an outer pouch containing a thermal chemical containing inner bag and a slidably received insulation sheet. The outer pouch is preferably made from flexible, transparent plastic, such as polyethylene.
U.S. Pat. No. 4,462,224 to Dunshee et al. discloses an instant hot or cold, reusable cold pack that consists of three separate compartments. By mixing the contents of two of the compartments, the user initiates a thermal reaction providing either heat or cold therapy. After this reaction has run its course, the contents of the third compartment may be mixed with the first and second compartments to produce a gel that is relatively soft and moldable when frozen.
U.S. Pat. No. 4,756,311 to Francis, Jr. discloses a microwavable gel pack wherein the gel is contained in an envelope fabricated from a stretchable laminate having an inner layer of polyethylene or polyurethane and an outer layer of nylon, nylon sclair, paper or a fabric. The laminate materials must not allow rupture of the pack when subjected to microwave energy of approximately full power of a microwave heating device for a period of time exceeding about two minutes but not exceeding about four minutes.
U S. Pat. No. 3,929,135 to Thompson discloses a top sheet having tapered capillaries for use in absorptive devices such as diapers, sanitary napkins, bed pads, incontinent pads, towels, bandages and the like. Other liquid impermeable sheets that are merely perforated without adding appreciably to the thickness of the sheet, such as Delnet.TM. Sheeting (commercially available from Hercules Chemical Co., Wilmington, Del.), are used as non-stick layers over absorbent materials in such items as wound dressings.